SUPER INVAR EAST COAST 3 Fir Court, Oakland, NJ 07436 201-337-9400 • Fax: 201-337-9698 Toll Free: 800-524-4309 Email: [email protected] WEST COAST 1335 East Warner Ave., Santa Ana, CA 92705 714-556-5561 • Fax: 714-556-5562 Toll Free: 877-632-9378 Email: [email protected] www.nealloys.com NATIONAL ELECTRONIC ALLOYS An ISO Certified Corporation Specialty Metal Service Center Dedicated to Customer Service & Quality Invar (36% NI-Balance Iron) Alloy has been the metal of choice for low expansion applications for years. “Super-Invar” (31% NI, 5% Co, Balance Iron) has found some favor because it has a near zero coefficient of thermal expansion over a limited temperature range. The useful range of “Super Invar” originally was limited to between –32° to + 275°C because the material begins to transform from Austenite to Martinsite at temperatures below –32°F. Because of the slight variations in chemistry in today’s version of this alloy, these ranges may fluctuate. In addition, the cold or hot working of material can affect these variables. Super Invar is tough and gummy, not hard or abrasive. Tools tend to plow instead of cut, resulting in long stringy “chips.” Tools must be sharp, feed and speed low to avoid heat and distortion. The use of a coolant is recommended for all machining operations. Machinability similar to Kovar, Stainless 300 series, and Monel Alloys has been reported. Ni-Fe Alloys generally have a tendency to develop a surface scale during hot working that penetrates the surface. For this reason machining allowances must be increased to eliminate the deep surface oxide. The initial cut is frequently the most difficult. CHEMICAL COMPOSITION % Chemical Element Super Invar Nickel 31.26 Chromium .03 Manganese .39 Silicon .09 Carbon .05 Aluminum .07 Sulfur .01 Cobalt 5.36 Copper .08 MECHANICAL PROPERTIES Property Super Invar Density 0.294 lb/cubic in Hardness 77 RB Tensile Strength 69800 psi Yield Strength 43900 psi Elongation 2” 38% Modulus of Elasticity 21.5 x 10 psi Poisson’s Ratio .234 Linear coefficient of thermal expansion cm. per cm. per °F x 10 –6 Temp. range – °F Super Invar 30 to 100 9.4 30 to 200 9.4 30 to 300 8.8 30 to 350 9.0 30 to 400 8.7 30 to 425 8.9 30 to 450 9.0 30 to 500 9.4 30 to 550 10.2 30 to 600 10.4 30 to 700 11.3 30 to 800 12.1 30 to 900 13.0 30 to 1000 13.9
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SUPER INVAR
EAST COAST3 Fir Court, Oakland, NJ 07436201-337-9400 • Fax: 201-337-9698Toll Free: 800-524-4309Email: [email protected] WEST COAST1335 East Warner Ave., Santa Ana, CA 92705714-556-5561 • Fax: 714-556-5562Toll Free: 877-632-9378Email: [email protected]
www.nealloys.comNatioNal ElEctroNic alloys
An ISO Certified Corporation
Specialty Metal Service Center Dedicated to Customer Service & Quality
Invar (36% NI-Balance Iron) Alloy has been the metal of choice for low expansion applications for years. “Super-Invar” (31% NI, 5% Co, Balance Iron) has found some favor because it has a near zero coefficient of thermal expansion over a limited temperature range. The useful range of “Super Invar” originally was limited to between –32° to + 275°C because the material begins to transform from Austenite to Martinsite at temperatures below –32°F. Because of the slight variations in chemistry in today’s version of this alloy, these ranges may fluctuate. In addition, the cold or hot working of material can affect these variables.
Super Invar is tough and gummy, not hard or abrasive. Tools tend to plow instead of cut, resulting in long stringy “chips.” Tools must be sharp, feed and speed low to avoid heat and distortion. The use of a coolant is recommended for all machining operations. Machinability similar to Kovar, Stainless 300 series, and Monel Alloys has been reported. Ni-Fe Alloys generally have a tendency to develop a surface scale during hot working that penetrates the surface. For this reason machining allowances must be increased to eliminate the deep surface oxide. The initial cut is frequently the most difficult.
CHEMICAL COMPOSITION %
Chemical Element Super Invar
Nickel 31.26
Chromium .03
Manganese .39
Silicon .09
Carbon .05
Aluminum .07
Sulfur .01
Cobalt 5.36
Copper .08
MECHANICAL PROPERTIES
Property Super Invar
Density 0.294 lb/cubic in
Hardness 77 RB
Tensile Strength 69800 psi
Yield Strength 43900 psi
Elongation 2” 38%
Modulus of Elasticity 21.5 x 10 psi
Poisson’s Ratio .234
Linear coefficient of thermal expansion cm. per cm. per °F x 10–6
Temp. range – °F Super Invar
30 to 100 9.4
30 to 200 9.4
30 to 300 8.8
30 to 350 9.0
30 to 400 8.7
30 to 425 8.9
30 to 450 9.0
30 to 500 9.4
30 to 550 10.2
30 to 600 10.4
30 to 700 11.3
30 to 800 12.1
30 to 900 13.0
30 to 1000 13.9
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